It’s a Bird! It’s a Plane!
… No! It’s a NOAA Weather Balloon!

Everyday, NOAA’s National Weather Service launches weather balloons from 102 sites throughout the United States, the Caribbean and the Pacific to help with weather forecasting.

But as the saying goes, what goes up must come down, eventually.

There’s No Need to Fear… NOAA is Here

If you happen to stumble upon a large, deflated balloon tethered to a plain white box with the words “Harmless Weather Instrument,” don’t be alarmed. This device is actually an important piece of weather equipment called a radiosonde – a battery-powered instrument that is suspended below the hydrogen- or helium-filled weather balloon.

As the balloon rises through the atmosphere, radiosonde sensors measure and transmit profiles of air pressure, temperature and relative humidity from the Earth’s surface to about 20 miles high in the sky. While in flight, radiosonde sensors also obtain data for wind direction and speed.

Radiosonde data are received by a ground-tracking receiver, which processes it for transmission to weather forecasters and other data users. This information is a primary source of upper-air data for weather prediction models.

The National Weather Service also uses radiosonde data to accurately assess and predict changes in the atmosphere. The data help forecasters identify and warn the public and pilots of severe weather, and helps verify satellite data and input for weather prediction models. The data also further research for weather and climate change.

Funny Looking, But Perfectly Safe

After the balloon reaches an altitude of about 100,000 feet, it eventually pops and the radiosonde falls to the ground. It can land in a wide variety of locations, such as in trees, on bridges and in backyards — sometimes more than 200 miles away from where it was launched.

Once it lands, the radiosondes can make some disconcerting noises and give off a sulfuric (egg-like) smell. However, a radiosonde and its attached flight equipment are perfectly safe. The unit includes a latex weather balloon that at launch is six feet wide, a radiosonde and twine, a chemical light and an orange parachute. None of these components are potential hazards for people.

Return to Sender, Please!

Radiosondes are easy to recognize, and each one has its own addressed, postage-paid return mailbag. However, the National Weather Service recovers less than 20 percent of the 75,000 radiosondes released each year.

The National Weather Service hopes that, through education and awareness of the value and importance of upper-air radiosondes, more people will be eager to return them. Returning radiosondes benefits the environment and saves taxpayer dollars by recycling the units for reuse.

So, if you happen to find a weather balloon and its radiosonde package in your neck of the wood, there’s no need to fear… Please return it to NOAA’s National Weather Service.